Yamah 115 slows after run

[diverjohn]

Hi all first post so hear goe's.

My Yamah 115hp has a strange fault after a 1 hr run at about 4,500 rpm, I throttled back for a big wave, the engine after that would not pick up but ran at low revs smothly if I opend the throttel any more it ran lumpy after a further 1 hour going back slowly it returned to full power? I have had new injectors fitted and had the fuel filters done even ran it from a fuel can, the oil is fine, the telltale was not hot and was running well, could it be low oil presure? or what do you think?

[99yam40]

Did you have any alarms or indication on the tach when it happened?
Are you sure your alarms will sound when a problem shows up?

If talking about oil pressure then this motor is a 4 stroke?

I would be looking at fuel pressures to see what is going on and get it hooked up to a computer to see if there are any codes

[diverjohn]

Yes its a 4 stroke and there were no alarms, hooking it up to a computer can I get a conection for my lap top or is it a dealer job?

thanks for the quick reply

[99yam40]

best to take to dealer as the cable and software is not something you can find just anywhere

[diverjohn]

can I check the oil presure and fuel presure? I have just changed the oil and filter, it slows after a long run the if you slow down and then after an hour it will go well again, I wash it out with frresh water after each trip, its used twice a week all year around and this is the first problem I have had with it, will it remember its faults or will it have to be hooked up on a run?